#include <iostream>
#include <string.h>
using namespace std;

const int N = 1e5 + 10;
const int M = 30;
char a[N];
int sum[M];

int main()
{
    int n;
    cin >> n;
    string s;
    cin >> s;
    int mmax = 0,mmax_index = 0;
    for(int i = 0;i < n; i++)
    {
        sum[s[i] - 'a']++;
        if(sum[s[i] - 'a'] > mmax)
        {
            mmax = sum[s[i] - 'a'];
            mmax_index = s[i] - 'a';
        }
    }

    if(mmax > n - mmax + 1)
    {
        cout << "no";
    }
    else
    {
        cout << "yes" << endl;
        int begin = 0;
        while(mmax)
        {
            a[begin] = mmax_index + 'a';
            mmax--;
            begin+=2;
        } 
        for(int i = 0;i < 26; i++)
        {
            if(i != mmax_index && sum[i])
            {
                while(sum[i]--)
                {
                    if(begin >= n)
                    {
                        begin = 1;
                    }
                    a[begin] = i + 'a';
                    begin+=2;
                }
            }
        }
        for(int i = 0;i < n;i++)
        {
            cout << a[i] ;
        }
        cout << endl;
    }


    return 0;
}